Manual assessment of cylinder rearing behavior is more sensitive than automated gait evaluations in young, male mice post-stroke of the forepaw somatosensory cortex.

BACKGROUND

Stroke is a leading cause of long-term adult disability. Behavioral testing with animal stroke models, which offers a way to evaluate the effectiveness of new interventions, currently relies on methods that are time- and labor-intensive. Automated behavioral assessments of locomotion and gait have been proposed as an alternative, but it is currently unknown whether they are sensitive enough to assess behavioral deficits following stroke of the forepaw somatosensory cortex. The purpose of this study was to compare a validated, manually assessed behavioral test, cylinder rearing (a measure of forepaw asymmetry during exploration), with automated behavior tests of locomotion in a rodent photothrombotic stroke model.

METHODS

We induced a focal photothrombotic stroke in young (12-16 week old) male mice over the left forepaw somatosensory cortex, conducted behavioral testing at acute (48 h) and sub-acute (4 weeks) time points post-stroke, and then correlated behavior deficits to histological measures.

RESULTS

Three automated behavioral tests were used in comparison to cylinder rearing: CatWalk (spontaneous gait), DigiGait (forced treadmill locomotion), and open field (a measure of general locomotor activity). Cylinder rearing testing showed significant forepaw asymmetry between stroke and sham groups acutely and sub-acutely after stroke. Catwalk, DigiGait, and open field tests showed no significant differences between groups. When correlating behavior to histological measures of stroke, the presence of secondary thalamic injury (STI) was associated with forepaw asymmetry on cylinder rearing.

CONCLUSIONS

These findings illustrate the need to find alternative automated behavioral measures for mouse photothrombotic stroke of the forepaw somatosensory cortex.